Alkoxy substituted sterically hindered phenols

ABSTRACT

Polyurethans stabilized against degradation and discoloration caused by the action of light or UV radiation, oxygen, substances present in the atmosphere, such as nitrogen oxides, and heat by the addition of alkoxy substituted sterically hindered phenols which has a 2-(2&#39;&#39;-hydroxy-3-&#39;&#39;-tertiary alkylbenzyl) anisole unit:

United States Patent 1191 Nast et al.

[ Mar. 26, .1974

[ ALKOXY SUBSTITUTED STERICALLY HINDERED PHENOLS [75] lnventors: Roland Nast, Cologne-Buchheim; Harald Oertel; Kurt Ley, both of Odenthal-Globusch, all of Germany [73] Assignee: Bayer Aktiengesellschaft,

Leverkusen, Germany 22 Filed: Apr. 1, 1971 21 Appl. No.: 130,506

Related US. Application Data [62] Division of Ser. No. 855,372, Sept. 4, 1969, Pat. No.

3,109,829 11/1963 Bown 260/613 R.X

Primary Examiner-Bernard Helfin Attorney, Agent, or Firm-Plumley & Tyner [57] ABSTRACT Polyurethans stabilized against degradation and discoloration caused by the action of light or UV radiation, oxygen, substances present in the atmosphere, such as nitrogen oxides, and heat by the addition of alkoxy substituted sterically hindered phenols which has a 2-(2-hydroxy-3-'-tertiary alkylbenzyl) anisole unit:

OH OCH! tert alkyl CH as stabilizers.

4 Claims, No Drawings OCH:

OH I tert aik 1-@-0 as stabilizers and furthermore to stabilized polyurethanes being stabilized with a synergistic mixture consisting of a) anisole and b) a 2-(2-hydroxyphenyl)- benzotriazole.

Polyurethanes prepared from high molecular weight polyhydroxyl compounds, polyisocyanates and chain lengthening agents which are widely used in the form of foams, elastomers, coatings, foils orv elastomer threads are unstable when exposed to the action of light and in some cases are also unstable to hot air. The instability depends to some extent on their structural make-up. This leads to mechanical deterioration and in many cases strong discoloration of the polyurethanes also occurs.

Many attempts have already been made to provide some protection against discoloration and degradation by the addition of antioxidants which are known per se, e.g., those based on phenols, but this stabilization is generally not sufficient.

Thus, for example phenols such as 4,4'-alkylid enebis-(6-tertiary butyl-m-cresol), 2,6-ditertiary butyl-4- methyl-phenol or 4,4-methylene-bis-(2,6-ditertiary butylphenol have been tested as stabilizers but they either initially discolor the polyurethane which is troublesome or they fail to provide protection against discoloration under the action of light or substances present in the atmosphere. The use of polyphenols such as l ,3,5-trimethyl-2,4,6-tris-( 3 ,5 -ditertiary butyl-4- hydroxy-benzyI)-benzene has also been proposed as stabilizers (German Auslegeschrift 1 243 866). Furthermore, numerous phenolic compounds have been mentioned which are said to be suitable for stabilizing polyurethanes when used together with hydroxybenzophenones (DAS l 106 490). The effect of these phenolic stabilizers, however, is not sufficient or is not wash resistant or the stabilizers themselves have a colour which makes them unsuitable e.g., for use with white elastomer threads.

A new class of phenolic stabilizers have now been found which owing to their typical structure provide a highly effective stabilization of polyurethanes. Moreover, these stabilizers are colourless, cause no discolouration of the polyurethane and provide substantially better, wash-resistant protection to discoloration and degradation under the action oflight and/or substances present in, the atmosphere.

The invention relatesto the use of 0.05 to percent by weight of alkoxy substituted, sterically hindered, 5 phenols of formula I in which T Represents a tertiary alkyl group, e.g., a tertiary butyl, tertiary amyl, tertiary octyl or tertiary dodecyl radical, preferably the tertiary butyl radical,

A represents a primary or secondary alkyl radical having 1 to 12 carbon atoms, preferably a methyl group or an isononyl group or the radical T,

R represents a primary alkyl radical having 1 to 12 carbon atoms, preferably a methyl group, or an aralkyl radical, preferably a benzyl group,

Q represents the group A or T, preferably a methyl, isononyl, tertiary butyl or tertiary octyl radical or an OR group, preferably a methoxy group or benzyloxy r up. n

X represents a hydrogen atom or a radical wherein the group CH 'X stands in the 6-position when Q is an alkyl group and in the 5-position when Q is an OR group as stabilizers for polyurethane elastomere.

It is preferred to use stabilizers of Formula II methyl radical, a tertiary alkyl radical, preferably a tertiary butyl or tertiary octyl radical, or a methoxy group and X represents a radical of the following formula C(CHi)! the position of CH 'X being related to the substituent Q as already defined above. The above stabilizers are preferably used in amounts of 0.2 to 3 percent by weight based on the polyurethane elastomers.

The phenolic compounds used are new compounds and can be prepared by reacting 2-tertiary-alkyl-4- alkylphenols with o-hydroxymethyl-alkoxybenzenes in the presence of catalytic quantities of strong acids, water being split off in the process, for example according to the following reaction equation:

(CHOzC HO-HzC I C (0139 p-toluenesulphonlc acid in boiling toluene OCH:

CHz-OH I OH O CH: (|)H (CHmC CH CH C (H,);

( 3H; Alkyl JJH;

(stabilizer A) The substantial improvement which can be achieved by using the alkoxy-substituted, sterically hindered phenols is demonstrated in comparison tests using, for comparison, corresponding compounds which contain a free hydroxyl group instead of the alkoxy substitutent. In the comparison tests, a phenol, namely 1,3,5- trimethyl-2,4,6-tris-(3,5-ditertiary butyl-4-hydroxybenzyl)-benzene which may be regarded as one of the most effective phenolic compounds of those previously known (DAS 1 243 866) is also included.

it is then found, inter alia, that equivalent phenols, e.g., the following trisphenol:

I on (1)11 (CHahC- CHr- C (CH9:

CIJH; CIJHI CIH: show a strong discoloration of their own (yellow), compared with the stabilizer A) according to the invention which contains an alkoxy group instead of the middle hydroxyl group, and they are therefore unsuitable for stabilising colourless polyurethanes. Also the alkoxy substituted phenols according to the invention show better stabilization to degradation than, for example, the pure phenolicstabilizer l,3,5-trimethyl-2,4,6- tris-(4-hydroxy-3,5-ditertiary butyl-benzyl)-benzene (according to DAS l 243 866). v

The following compounds are examples of suitable alkoxysubstituted, sterically hindered phenols which may be used according to the invention for stabilizing the polyurethanes:

2,4-Dimethyl-6(2-hydroxy-3-tertiary methyl-benzyl)-0-benzyl-phenol v 2 ,4-dimethyl-6-( 2 '-hydroxy-3 -tertiarybutyl-5 '-methyl-benzyl)-anisole 2-methyl-4-tertiary butyl-6-(2-hydroxy-3-tertiary butyl-5'-methylbenzyl)-anisole l 2-methyl-4-tertiary amyl-6-(2'-hydroxy-3-tertiary hutyl-SmethylbcnzylJ-anisole 6O butyl-5 yl-5 -methyl-benzyl )-anisole 2-methyl-4-tertiary butyl-6-( 2-hydroxy-3 tertiary butyl-S-methylbenzyl)-0-benzyl-phenol.

4-methyl-2,6-bis-( 2-hydroxy-3 -tertiary butyl-5 methylbenzyl)-anisole 4-methyl-2,6-bis-( 2 -hydroxy-3 -tertiary amyl-S methyl-benzyl )-anisole 4-methyl-2,6-bis-(2 -hydroxy-3 '-tertiary octyl-S methyl-benzyl)-anisole 4-methyl-2,6-bis-( 2-hydroxy-3 tertiary dodecyl-S methyl-benzyl)-anisole 4-methyl-2,6-bis-(2'-hydroxy-3'-tertiary methyl-benzyl)-butoxyphenol 4-tertiary butyl-2,6-bis-(2-hydroxy-3'-tertiary butyl 5-methyl-benzyl)-anisol 4-tertiary butyl-2,6-bis-( 2-hydroxy-3 -tertiary amyl- 5 methyl-benzyl )-anisole 4-tertiary amyl-2,6-bis-(2-hydroxy-3'-tertiary butyl- 5 '-methyl-benzyl)-anisole 4-tertiary octyl-2,6-bis-(2-hydroxy-3-tertiary butyl- 5 methyl-benzyl )-anisole 4-tertiary dodecyl-2,6-bis-(2-hydroxy-3'-tertiary butyl-5 -methyl-benzyl )-anisole 4-isononyl-2,6-bis-(2-hydroxy-3'-tertiary butyl-5- methyl-benzyl)-anisole 4-isopropyl-2,6-bis-(2-hydroxy-3'-tertiary butyl-5- methyl-benzyl)-anisole 4-methyl-2,6-bis-( 2 '-hydroxy-3 '-tertiary methyl-benzyl)-0-benzyl phenol 2,5-bis-( 2 '-hydroxy-3 '-tertiary benzyl)-hydro-quinone-dimethylether 2,5-bis-(2-hydroxy-3-tertiary octyl-5'-methylbenzyl)-hydro-quinone-dimethyl ether.

2,5-bis-(2-hydroxy-3'-tertiary dodecyl-5-methylbenzyl-hydroquinone-dimethyl ether 2,5-bis-(2-hydroxy'3'-tertiary butyl-5-isopropylbenzyl-hydroquinone-dimethyl ether 2,5-bis-(2-hydroxy-3'-tertiary butyl-5-tertiary butyl-benzyl)-hydroquinone-dimethylether 2,5-bis-( 2 -hydroxy-3 -tertiary benzyl)-hydroquinone-dimethyl ether A further object of the invention relates to stabilized polyurethanes having incorporated 0.05 to 5.0 percent by weight of a stabiliser mixture consisting of a. an alkoxy substituted, sterically hindered phenol and y b. a 2-(2-hydroxyphenyl)-benzotriazole for stabilising polyurethanes. The alkoxy substituted, sterically hindered phenols which are used have the following formula:

butyl-5 butyl-5 butyl-S '-methylamyl-S '-methylin which tyl, tertiary amyLtertiary octyl or tertiary dodecyl radical (preferably a tertiary butyl radical);

A represents a primary or secondary alkyl radical containing 1 to 12 carbon atoms, preferably a methyl group or the same as the group T;

R represents a primary alkyl radical containing 1 to 12 carbon atoms or a benzyl radical, preferably a methyl group;

O A and is preferably a methyl, tertiary butyl or tertiary octyl radical or an isononyl radical or an OR radical, preferably a benzyloxy or a methoxy group;

X represents a hydrogen atom or a radical of the formula the radical C l-l .X being in the 6-position when Q alkyl and in the 5-position in the case when Q OR.

The 2-(2'-hydroxyphenyl)-benzotriazoles used have the following formula:

N H0 it (IT) in which X represents a hydrogen atom, an alkyl group or a halogen atom;

Y represents a hydrogen atom, an alkyl radical containing l to 12 carbon atoms or an alkylene radical which has hetero atoms, preferably a tertiary alkyl radical, e.g., tertiary butyl, tertiary amyl or tertiary dodecyl; and

R represents a hydrogen atom or an alkyl group containing l to 12 carbon atoms, e.g., methyl, ethyl, isopropyl, tertiary butyl, tertiary amyl, tertiary octyl or tertiary dodecyl.

Compounds a) and b) are used in proportions by I weight of 1:10 to :1 in the mixture. This results in a synergistically active stabilisation to discolouration and degradation by light, heat and atmospheric impurities being imparted to the polyurethane elastomers.

The use of 2-(2'-hydroxyphenyl)-benzotriazoles as stabilising additives in polymers is known per se but their effect is quite inadequate when used on their own as stabiliser. A combination of 2-(2-hydroxyphenyl)- benzotriazoles and l,3,5-trimethyl-2,4,6-tris-(3,5- ditertiarybutyl-4-hydroxybenzyl)-benzene or l,2,4,5- tetramethyl-3 ,6-bis-( 3 ,S-ditertiarybutyl-4-hydr0xybenzyl)-benzene has also been described for stabilising segmented polyurethanes in Dutch Auslegeschrift NE 6,5- 09,745. These additives do provide a certain amount of protection but it is insufficient and the need remains for a highly effective, wash-resistant stabiliser for elastomers, especially for elastomer threads.

Compound (b) is preferably a benzotriazole of the following formula:

Q X N OH Y 6 in which X represents a hydrogen or chlorine atom;

Y represents a hydrogen atom or an alkyl group containing l to 12 carbon atoms, preferably a tertiary alkyl group, e.g., tertiary butyl or tertiary amyl, or an N- methylene-phthalimido radical; and

T represents a hydrogen atom or an alkyl group containing l to 12 carbon atoms, e.g., a methyl, ethyl, isopropyl, tertiary butyl or tertiary amyl group.

The synergistic increase in effect obtained by using the stabiliser mixture instead of the same quantity of one or other of the individual components is clear from the results given in the Examples.

The great improvement in the resistance of polyurethane elastomers to discolouration and degradation which can be obtained by using alkoxy substituted, sterically hindered phenols of formula (I) in combination with light protective agents of formula (ll) is also demonstrated by comparison tests with a corresponding combination of phenol and light protective agent in which the phenol used is 1,3,5-trimethyl-2,4,6-tris- (3,5-ditertiary butyl-4-hydroxybenzyl)-benzene.

The following compounds may be mentioned by way of example as light protective agents based on 2-(2- hydroxyphenyl)benzotriazole which are used as component B of the synergistic stabiliser mixture:

2-( 2 -hydroxy-5 -methyl-phenyl )-benzotriazole 2-(2-hydroxy-5-methyl-phenyl)-chlorobenzotriazole 2-(2-hydroxy-3'-tertiary benzotriazole 2-(2'-hydroxy-3'-tertiary butyl-5-methyl-phenyl)-5- chloro-benzotriazole 2-(2-hydroxy-3'-methyl-5-tertiary benzotriazole 2-(2-hydroxy-3-methyl-5-tertiary butyl-phenyl)-5- lqrgsn m z e 2-(2-hydroxy-3,5-dimethyl-phenyD-benzotriazole 2-( 2-hydroxy-3 ',5 '-dimethyl-phenyl )-5-chlo'robenzotriazole 2-(2-hydroxy-3,5-ditertiary benzotriazole 2-(2'-hydroxy-3,5-ditertiary chloro-benzotriazole 2-(2'-hydroxy-3,5'-ditertiary benzotriazole 2-( 2 -hydroxy-3 ',5 '-ditertiary chloro-benzotriazole 2-(2-hydroxy-3,5'-ditertiary benzotriazole 2-( 2'-hydroxy-3 ,5'-ditertiary chlorobenzotriazole 2-(2-hydroxy-3'-N-methylene-phthalmiido)- benzothiazole.

butyl-5-methyl-phenyl)- butyl-phenyl)- butyl-phenyl)- butyl-phenyl)-5- amyl-phenyl)- amyl-phenyl)-5'- octyl-phenyl)- octyl-phenyl )-5- Other suitable hydroxyphenylbenzotriazoles are mentioned, for example, in German Auslegeschriften 1,213,408; 1,213,409 and 1,213,410 and in US. Patent Specification 3,213,058.

The elastic polyurethane which are to be stabilized and which may be in the form of foams can be produced by processes known per se from known starting materials. The polyurethanes are generally produced by reacting high molecular weight polyhydroxyl compounds (e.g., polyesters or polyethers which have a molecular weight of about 500 to 5,000 and melting points preferably below 60C) and aliphatic, araliphatic or aromatic polyisocyanates (preferably aromatic diisocyanates such as toluylene diisocyanate or diphenylmethane-4,4-diisocynanate) and so-called chain lengthening agents, i.e., low molecular weight compounds (molecular weight e.g., 18 to 400) which have two or more groups which are reactive with isocyanate (e.g., low molecular weight diols, diamines, dihydrazines, hydroxyhydrazines, semicarbazi hydrazides or also water) in a single stage of multistage process in a melt or in solvents by one of many known variable processes.

The following are given as examples of starting material: Polyesters of adipic acid and dialcohols having 2 to about carbon atoms, preferably those which have more than 5 carbon atoms, the dialcohols being optinally used for lowering the melting points of the polyesters in the mixture: polyesters of caprolactone and dialcohols; furthermore, polyalkylene ether diols, especially polytetramethylene ether diols, polytrimethylene ether diols, polypropylene glycol or corresponding copolyethers. The diisocyanates used are preferably aromatic diisocyanate, araliphatic diisocyanate such as m-xylylene diisocyanate or also aliphatic diisocyanates such as hexamethylene diisocyanate and dicyclohexylmethane-4,4-diisocyanate. Suitable chain lengthening agents are water, dihydric or trihydric such as butane dio; and/or p-xylylene glycols, trimethylol propane, diamines such as diphenylmethane-4,4'-diamine or 3,3- dichloro-dipehnylmethane-4,4'-diamine, isophorone diamine, metaxylylene diamine as well as hydrazine or di-hydrazides such as carbodihydrazide, oxalic acid dihydrazidem malonic acid dihydrazide, terephthalic acid dihydrazide or semicarbazidehydrazides such as B-semicarbazido-alanyl hydrazide.

The polyurethanes which are to be stabilized are preferably of the type which in addition to containing urethane groups also contain NH-CO-NH groups produced by reacting isocyanate groups with water or with compounds containing terminal NH groups (e.g., diamines, dihydrazides, carbodihydrazide or hydrazine) and which have a substantially linear, segmented molecular structure, are soluble in highly polar solvents such as dimethylformamide or dimethylacetamide and the characteristic segments of which can be represented by the following group.

In this formula, R represents a divalent aliphatic, araliphatic or aromatic radical derived from a diisocyanate, G represents the radical of high molecular weight polyhydroxyl compound of molecular weight 500 to 5,000 and melting point below 60C without its termial hydroxyl groups (e.g., radical of a polyalkylene ether, polyester, polyacetal or poly-N-alkyl urethane) and X represents the radical of a divalent chain lengthening agent which has terminal NH groups without the terminal NH groups e.g., an aliphatic, oraliphatic, aromatic or heterocyclic radical, an HN-CO-alkylene-CO- NH radical, an Nl-l-CO-Nl-l-(CH -CO-NH radical or a bond between two N atoms. The synthesis of such polyurethane (ureas) has been described in detail in German Auslegeschrift 1,270,276. Polyurethane foams can be produced by known processes and according to 8 known recipes (see e.g., Kunststoff-Handbuch, Volume VII, polyurethane, Publishers Carl Hanser Verlag Munich, 1966, pages 440 to 457, 504 to 531) e.g., with the addition of the stabilizers to the starting components (e.g., polyethers).

The stabilizers can be incorporated in the polyurethanes by any method suitable for the technical requirements of the process. The simplest method consists in adding the stabilizers, if desired in solution, to solutions of the polyurethanes, e.g., to solutions in highly polar solvents such as dimethylformamide or dimethylsulphoxide which are advantageously used for spinning, coating or coagulation purposes. The stabilizers may, however, also be incorporated in melts or plasticized polyurethane sheets by means of suitable mixing devices such as kneaders or rollers. Elastomer threads may have the stabilizers applied to the surface together with the dressing.

It is also possible to add the stabilizers to the starting materials used for the production of polyurethanes and only then carrying out the polyurethane synthesis. Thus alkoxy-substituted compounds are soluble in higher molecular weight polyhydroxyl compounds such as polyesters or polyethers. Suitable polyurethane syntheses, e.g., for the production of foams or elastomers, can then be carried out with such stabilizer-containing polyesters or polyethers. The stabilizers may also be added to the diisocyanates or to the NCO-termulated prepolymers produced from higher molecular weight polyhydroxyl compounds and (excess molar quantities) of diisocyanates, before the polyurethane is produced, e.g., by spinning it into aqueous diamine solutions. Discoloration of the polyurethanes can be prevented during synthesis by adding stabilizers during the reaction on NCO prepolymers with chain lengthening agents such as diamines, hydrazine, hydrazides or similar chain lengthening agents in highly polar solvents such as dimethylformamide or dimethylacetamide. The amount of stabilizers to be added is 0.05 to 10 percent by weight, preferably 0.2 to 3.0 percent by weight based on the solid polyurethane substance.

A further increase in the light protective effect is observed by adding the stabilizers according to the invention to polyurethane which contain reaction components having tertiary, aliphatically substituted amino groups in quantities of 0.02 to 1 mol and preferably 0.05 to 0.3 mol pre kilogram of elastomer substance. Examples of such reaction components are glycols, diamines, dihydrazides and polyesters or polyethers with tertiary amino groups e.g., N,N'-bis-(/3-hydroxypropyl)methylamine, N,N'-bis-(B-hydroxyethyl)- piperazine, N,N'-dimethyl, N,N-bis-(y-aminopropyl)- ethylene diamine, N,N'-bis-'yaminopropyl)-piperazine or polyethers containing tertiary amino groups or polyesters containing tertiary amino groups which are prepared by using dialcohols which contain tertiary amino groups.

PREPARATION OF THE ALKOXY SUBSTITUTED, STERICALLY HINDERED PHENOLS A Z-tertiary-alkyl-4-alkyl-phenol is condensed with an alkoxybenzene which contains one or two hydroxymethyl groups in the ortho-position to the alkoxy group in an organic solvent in the presence of catalystic quantities of a strong acid. The strong acid may be, e.g. ptoluenesulfphonic acid, phosphoric acid, sulphuric acid or hydrochloric acid or a strongly acid ionic exchanger.

The water produced on condensation may, if desired be removed by azeotropic distillation. Suitable solvents are, for example, benzene, toluene, cleaning petrol, cyclohexane, methanol, ethanol, glacial acetic acid, dioxane or chlorinated hydrocarbons such as chloroform or ethylene chloride.

A preferred, general method of carrying out the condensation is described below:

The mixture of a 2-tertiary alkyl-phenol and an ohydroxymethyl alkoxy-benzene is heated to boiling in a water separator in the presence of catalytic quantities of strong acid, such as p-toluen-sulphonic acid in an organic solvent which is immiscible with water, e.g., toluene, until water ceases to be split off. The hydroxymethyl compound may be introduced in solid form, as a solution or as a melt in small portions over a relatively long period into the boiling reaction mixture. The reaction product is generally precipitated in crystalline form on cooling and is' worked up in the usual manner e.g., by filtration or recrystallisation.

The alkoxybenzenes with one or two hydroxymethyl groups are known or can be prepared by analogous processes.

PREPARATION OF 4-METHYL-2,6-BlS-( 2'-HYDROXY-3 -TERTIARY- BUTYL-S '-METHYL-BENZYL)-ANISOLE (STABILIZER A) A solution of 200 g (1.22 mol) of Z-tertiary-butyl-pcresol and l g of p-toluenesulfphonic acid in 500 ml of 30 (Stabilizer A) are obtained in the form of colourless crystals, m.p. l88l90C.

A further 24 g of m.p. l88l89C are botained by concentrating the filtrate by evaporation.

The substances mentioned in the following Table l were prepared by an analogous procedure after reacting the given starting materials in the given molar ratios.

H; HI

'lAB LE 1 M. Molar o! sta- Stabilizer Starting materials ratios bilizers B 0H OCH; OH OH OCH; 2:1 194-197 1 -CIIz -CII -IIO-Cllz CHzOII ll-I3 -l- (El-Ia 5H3 i (F pisss9 C 0H OCH; 0H OCH: 1:1 119420 CH CH; Hr-crr2 @cm I I C H; A711 (1H C H;

(Kp. 145147/14 torr) D OH OCH; OH OH OCH; 1:1 172 4@-0H CH HOCHp@-CH:OH

H; H; 27H: T

(Fp. 104-106) E (RH OCH; CH; OH OCH; 2:1 226 C H H O C H 2 --G H C Hz-O H 1 l g l l H 0 CH3 H CH3 0 CH (Fp. 162463") I Approx. +=tert. butyl. -H=tert. octyl.

EXAMPLE 1 800 Parts of a polytetramethylene ether diol (molecular weight 1,010), 17.4 parts of N,N-bis-(B-hydroxypropyDQl-methylamine, 306.6 parts of solid elastomer substance) of titanium dioxide (rutile).

Portions of this elastomer solution (viscosity 423 poises) with and without stabilizer are converted into films in the usual manner and these films are cut up into threads which are then exposed to UV light (Fadeometer) (see Table 2).

In a similar reaction to that described in the above Example, 2 percent by weight of stabilizer A (6.52 parts) were not added subsequently to the finished elastomer solution (see above) but dissolved in dimethylformamide together with the ethylene diamine, and the elastomer solution was then prepared from the NCO prepolymer. A homogeneous, viscous, completely colourless elastomer solution which did not discolour even on exposure to air was obtained. After the solution had been cast to form films and the threads had been exposed to light, a practically identical stabilizing effect against mechanical degradation under exposure EXAMPLE 2 6,500 Parts of a copolyester (molecular weight 1,66-

0) of adipic acid and the diol mixture of 1,6-heanediol and 2,2-dimethylpropanediol in the molar ratio of :35 are first dehydrated for one hour at 130C/10 mm Hg, and 129 parts of N,N-bis-(B-hydroxypropyl)- N-methylamine 211g 1 ,782 parts of d ip henylmethane -4,4-diisocyanate are then added thereto at 55C and the reaction mixture is then heated in a boiling water bath (about minutes) until the NCO content of the NCO prepolymer melt is 2.2 percent.

820 g of a 33 percent titanium dioxide paste is intro duced into a solution, heated to about C, of 297.5 parts of B-semicarbazidoalanylhydrazide (H N-Nl-l-CO- 'NH-CH 'CH 'CO'NH-NH in 18,813 parts of dimethylformamide, and thereafter 6,460 parts of the NCO prepolymer melt are stirred into this mixture, a fairly viscous elastomer solution (615 poises/20C) being obtained.

Different portions of the leastomer solution are treated with different stabilizers according to the invention or with comparison substances and exposed in part in the Fadeometer in the form of elastomer films (see Table 3) and in part exposed in the Fadeometer after they have been spun into elastomer threads, and the mechanical degradation of the threads is determined (see Table 4). Spinnung was carried out b the dry spinning process by extruding the elastomer solution through a nozzle having 16 apertures of 0.2 mm diameter into a heated shaft (220 to 230C and drawing off the threads at a rate of about m/min and winding them at about m/min. Threads (total titre about to light was measured. 35 den) were then tempered for one hour at 130C.

TABLE 2 Fadeometer Exposure Stabilizer Before exposure to 22 hours 44 hours 66 hours 88 hours light Tensile Elongu- Tensile Elonga- Tensile Elnnga- Tensile Elonga- Tensile Elongation '71 strength tion "/1 strength tion strength tion 71/ strength tion strength g/dcn g/den g/den g/dcn g/den Without the addition of 0.60 584 0.03 100 not measurable stabilizer Discoloration: almost yellow yellowish brown yellowish brown yellowish brown colorless +2% stabilizer A 0.60 585 0.60 586 0.59 587 0.58 580 0.l8 330 Discoloration: colorless almost colorless almost colorless slightly yellowish colorless TABLE 3 i V Comparison tests with a stabilizer which contains a 55 cycloalkyl radical (compound F) instead of the tertiary Discoloration after exposure in the Fadeometer for alkyl radicals:

Stabilizer 480 min 900 min 1440 min 2 percent almost yellowish intensely compound F colourless yellow Without additive almost yellow brown yellow brown colourless 6Q 2% Stabilizer almost yellowish yellow according to colourless DAS l 243 866 0.5% stabilizer A colourless colourless colourless 2% Stabilizer A colourless colourless colourless OH 2% Stabilizer B colourless colourless almost i colourless 5 H, 2% Stabilizer C colourless colourless almost 1 2 colourless 2% Stabilizer D colourless colourless almost colourless 2% Stabilizer E colourless colourless yellowish L H 13 14 It is clear from the results given in the Table that the TABLE alkoxy substituted, sterically hindered phenols accordpmmrm-s of mm mils ing to the invention have a very good stabilizing action $313,353;133%,! which exceeds that of known efficient stabilizers. If the LM tertiary alkyl group in the stabilizers according to the 5 invention is replaced by a cyclohexy] group the Without stabilizer t ziilt i feii i'bllow ti gf t l t t ion stabilizing effect on polyurethanes, which effect is free 2 O h from discoloration, is lost. OH i preserved. V 1 0 -OH -CH2- EXAMPLE 3 I I CH3 CH 1,000 Parts of a polytetramethylene ether diol (OH number 1 l l 20.6 parts of N,N-bis(B-hydroxypropyl)- CH3 N-methylamine, 369 parts of parts of diphenylme- (stabilizer A).

thane-4,4'-diis0cyanate and parts of chlorobcn- OH OII OH n yeuow -Mechanical zene are heated at 65 to 70C for 50 minutes to form I I brown. if fig ig the NCO prepolymer. After cooling, the NCO content is 1.69 percent. I

5.27 Parts of ethylene diamine are dissolved in 895 g of DMF and treated with 13 parts of very finely di- 1 vided pigment (rutile) followed by 15 parts of solid car- CH3 CH3 bon dioxide, (comparison substance).

400 Parts of the NCO prepolymer solution are stirred 2% OH OCHa Foils 0010b Mechanical into this suspension in the course of a few minutes, an I 1958- tf elastomer solution having a viscosity of 565poises/20C C H CH3 prcsmv being obtained. Portions of the solution were treated with 2 percent of stabilizer A and B, respectively, and suitable known comparison substances which had a I free hydroxyl group instead of a methoxy group. Films (stabilizer C).

were produced in known manner from portions of the solution with and without stabilizer and exposed in the Foils intense Mechanical 01 I on allow to strum Lh Fadeometer (see Table 5). allow substantially The results show that the new stabilizers are greatly v superior since they do not give rise to any discoloration on exposure to light. Although the known compounds may also delay the mechanical degradation to some ex- CH3 Cm tent, they undergo severe discoloration in the process o b t and are therefore unsuitable for colourless articles such (0 mpauson Su 5 as foils or threads 2% OH OCHa OH Foils color- Mechanical less. strength 40 preserved.

CH2 -CH2- EXAMPLE 4 800 Parts of a polytetramethylene ether diol (OH number 1 l l) are heated to to C for 50 minutes In H with 17.4 parts of N,N-bis-(B-hydroxypropyl)-N- 5 a methylamine, 306.6 parts of diphenylmethane-4,4'- (amulet TABLE 4 Mechanical degradation of elastomer threads (individual titre approximately 12 den) after Fadeometer exposure Before exposure 480 min 900 min 1440 min Elongation at Tensile Elongation at Tensile Elongation at Tensile Elongation at strength g/den break strength g/den break strength g/den break strength g/den break 7:

without 0.54 400 0.4l 350 0.12 stabilizer 2% Stabilizer 0.55 370 0.50 350 0.42 340 330 A 0.33

2% Stabilizer 0.55 400 0.5! 370 0.46 385 300 A, but threads 0.30 washed for 3 hours* 2 Stabilizer 0.55 400 0.47 400 0.33 335 300 according to 0.34 DAS 1,243,866

' Treated for 3 hours in a solution of 5 gll of soup -v- 2 gll of soda at 60C.

Portions of the above elastomer solution are treated with 2 percent of stabilizer A according to the invention.

The elastomer solutions, with and without stabilizer, are painted on glass plates and dried at 100C for 60 minutes. The elastomer films, which are about'0.15 to 0.20 mm in thickness, are cut up into threads of about 300 den with a foil cutting machine and then exposed to UV. light in a Atlass Fadeometer for 0,22 and 66 hours.

If elastomer solution I is treated with 2 percent by weight of stabilizer A, slightly coloured elastomer threads are obtained which are substantially more stable on exposure to light and treatment with hot air (e.g., one hour at 150C) than the threads obtained from elastomer solution 1 without the addition of stabilizer.

EXAMPLE 6 800 Parts of polytetramethyleneether diol, molecular weight 1,010, are heated at 70C for minutes with 17.35 parts of N,N-bis-(B-hydroxypropyl methylamine, 326.5 parts of diphenylmethane-4,4- diisncyanate and 287 parts of chlorobenzene to form the NCO propolymer. By stirring 408 parts of the prepolymer into a solution, heated to about 60C, of 10.7 parts of carbodihydrazide in 960 parts of dimethylformamide, a highly viscous (600 poises) elastomer solution is obtained. A part of this solution is treated with 1 percent by weight of stabilizer A (based on the amount of solid substance) and another part is left without stabilizer. Films obtained from the solutions yield the following values after exposure in the Fadeometer:

TABLE 6 Fadeometer exposure (in hours) Stabilizer Before exposure 22 hours 44 hours Tensile strength Elongation at Tensile strength Elongation at Tensile strength Elongation at break (g/den) break (70) (g/den) break (70) (g/den) Without the 0.65 600 0.05 142 no longer measurable addition of stabilizer Discoloration: almost colorless yellow brown yellow brown 2% Stabilizer A 0.66 605 0.60 620 0.53 621 Discoloration: colorless colorless colorless EXAMPLE 5 TABLE 7 800 Parts of a polytetramethylene ether diol (OH number 1 l l are heated together with 18.0 parts ofN,- N-bis-(fl-hydroxypropyl)-N-methylamine, 394.5 parts of diphenylmethane-4,4-diisocyanate and 304 parts of chlorobenzene at 80C for 40 minutes, an NCO prepolymer being formed which contained 3.58 percent of NCO after it had cooled to room temperature. Elastomer solution I:

404 Parts of the NCO prepolymer solution and 3.30 parts of water in 889 parts of dimethylformamide are stirred together at room temperature, the solution becoming yellow after about one hour and a highly vicous, deep yellow elastomer solution being obtained after 24 hours. When the solution is spun by the usual dry spinning process, yellow elastomer threads are obtained. Elastomer solution II:

404 Parts of the NCO prepolymer solution, 3.30 parts of water and 6.4 parts of stabilizer A (2 percent by weight) in 890 parts of dimethylformamide are stirred together at room temperature, a highly viscous, completely colourless elastomer solution being obtained after 24 hours, this solution yielding colourless elastomer threads when spun by conventional dry spinning processes, which threads also have substantially better stability against discoloration and mechanical degradation when exposed to light or treated with hot air than the threads from elastomer solution 1.

Tensile strength (in g/den) after Fadeometer exposure (in hours):

800 Parts of a polytetramethylene ether diol (molecular weight 1010), 17.4 parts of N,N-bis-(B-hydroxypropyl)-N-methylamine, 306.6 parts of 4,4- diphenylmethane-4,4-diisocyanate and 284 parts of chlorobenzene are heated to 65 to C for 52 minutes and then cooled to room temperature. 400 Parts of this NCO prepolymer solution (1.88 percent NCO) are introduced with rapid stirring in the course of 4 minutes into a fresh suspension prepared by adding 15 parts of solid carbon dioxide to a solution of 5.93 parts of ethylene diamine in 898 parts of dimethylformamide, a homogeneous, viscous slightly yellowish elastomer solution is obtained. This solution is pigmented by the addition of 4 percent by weight (based on solid elastomer substance) of titanium dioxide (rutile). Different portions of the elastomer solution (viscosity 423 P) with and without the addition of stabilizer are converted into films as described in Example 4, and these films are cut up into threads which are then exposed to UV light (Fadeometer) (see Table 8).

In a similar reaction as in the above example, the 2 percent by weight of stabiliser were not added subsequently to the finished elastomer solution (see above) but dissolved in dimethylformamide together with the ethylene diamine, and the elastomer solution was then prepared from the NCO prepolymer. A homogeneous, viscous, completely colourless elastomer solution was obtained which was not discoloured even on exposure to air. After the solution had been cast into films and the threads had been exposed, the stabilising effect against mechanical degradation under exposure to light was found to be practically identical.

EXAMPLE 8 Preparation of the polyurethane:

6500 Parts of a mixed polyester (molecular weight 1660) of adipic acid and the diol mixture of 1,6- hexanediol and 2,2-dimethyl-propanediol in the molar ratio of 65:25 are dehydrated for one hour at 130C/l0 N-methylamine and 1,782 parts of diphenylmethane 4,4-diisocyanate are then added at C and the reaction mixture is heated in a boiling water bath (about minutes) until the NCO content of the NCO prepolymer melt is 2.22 percent.

820 G of a 33 percent titanium dioxide paste are introduced into a hot solution of 297.5 parts of B-semica rbazido-alanyl-hydrazide (H NNH'CO'NH'CH 'CH -CO'NH'NH in 18,813 parts of dimethylformamide at approximately C, and 6,460 parts of the NCO prepolymer melt are then stirred in, a highly viscous elastomer solution being formed (650 poises/20C).

Different stabilisers according to the claim of the invention and comparison substances are then added to different portions of the elastomer solution, and after the solution has been spun into elastomer threads, the threads are exposed in a Fadeometer and their mechanical degradation is determined (see Table 9). Spinning was carried out by the dry spinning process, the elastomer solution being extruded through a nozzle which had 16 apertures of 0.2 mm diameter into a heated shaft (220 to 230C), the threads being drawn off at a rate of about m/min. and wound at the rate of about m/min. The threads (total titre about 190 mm Hg. and 129 parts of N,N-bis-(B-hydroxypropyl)- 25 den) were then tempered at 130C for one hour.

TABLE 8 Fadeometer Exposure Initially 22 Hours 44 Hours 66 Hours 88 Hours Stabiliscr Tensile Elonga- Tensile Elonga- Tensile Elonga- Tensile Elonga- Tensile Elongation 71 Strength tion 70 Strength tion Strength tion 72 Strength tion Strength g/den g/den g/den g/den Without the addition of 0.60 584 0.03 100 not measurable stabiliser Discolouration: yellow yellow brown yellow brown yellow brown almost colorless 2% Stabiliser A 0.60 585 0.60 586 0.59 587 0.58 580 0.]8 330 (component a) of the synergistic mixture) Discolouration: colorless almost colorless almost colorless pale yellowish colorless 2% 2-(2hydroxy-3' tcrtiary 0.39 526 no longer measurable butyl-S' methyl-phcnyl)-5- chlorobenzotriazole (component b) of the synergistic mixture) colorless yellowish yellow +l% stabiliser A +17: 0.7] 604 0.60 570 0.59 546 0.50 534 2-(2'-hydroxy-3' tertiary butyl-S' -methyl-phenyl)-5- chlobenzo-triazole (synergistic mixture) Colorless colorless colorless colorless colorless +19! lONOX 330 +l7t 0.69 573 0.58 550 0.52 540 0.20 385 2 (2'hydroxy-3'-tertiary butyl 5'-mcthylphenyl)-5- chloro-benzotriazole (mixture according to Dutch 6.509.745)

colorless colorless colorless colorless yellowish TABLE 9 Mechanical degradation of elastomer threads (individual titre about 12 den) after Fadeometer exposure Initially 480 Minutes 900 Minutes 1440 Minutes Tensile Elongation Tensile Elongation Tensile Elongation Tensile Elongation at Strength at break 7: Strength at break 7: Strength at break 7: strength break 7:

g/den g/den g/den g/den Without stabiliser 0.54 400 0.41 350 0.12

TABLE 9 -Cntinucd Mechanical degradation of clastomer threads (individual titre about 12 den) after Fadeomcter exposure Initially 480 Minutes 900 Minutes 1440 Minutes Tensile Elongation Tensile Elongation Tensile Elongation Tensile Elongation at Strength at break Strength at break 7: Strength at break 7!. strength break 7:

g/den g/den g/den g/den 27( Stabiliser A 0.55 370 0.50 350 0.42 340 0.33 330 2% 0.42 340 0.15 195 3'(2'-hydroxy-3,5'-ditertiary butylphenyl)--chlorobenzotriazole 171 stabiliser A 1% 0.64 400 0.62 390 0.52 385 0.50 350 2-(2'-hydroxy-3 5-ditertiarybutylphenyl)5 chlorobenzotriazole (synergistic mixture) 1% stabiliser according to DAS 0.55 400 0.54 400 0.44 335 0.28 310 1,243,866 (KONOX 330) l7r(comparison test according to Dutch 6,509.745)

After a washing treatment (3 hours in a solution of 5 g/l soap 2 g/l soda at 60C) the following values are obtained for the synergistic mixture and the mixture used in the comparison test according to Dutch Patent 6.509.745, demonstrating the increased wash resistance of the synergistic mixture according to the invention.

Synergistic mixture after washing 0.64 (see above) Comparison test according to Dutch Patent 6,509,745 after washing (see above) The results show that the mixture of compounds a) and b) has a synergistic effect compared to the individual compounds of the same concentration and that the stabilising effect is distinctly better than that of known stabiliser mixtures (e.g., according to Dutch Pat. No. 6- ,509,745) and that it is better preserved after washing.

EXAMPLE 9 Preparation of the polyurethane solution:

1,000 Parts of a polytetramethylene ether diol (Ol-l number 1 1 1), 20.6 parts of N,N-bis-(B-hydroxypropyl)-N-methylamine, 369 parts of diphenylmethane-4,4'-diisocyanate and 349 parts of chlorobenzene are heated to 65 to 70C for 50 minutes to form the NCO prepolymer. After cooling, the NCO content is 1.69 percent.

5.27 Parts of ethylene diamine are dissolved in 895 g of DMF and treated with 13 parts of very finely divided pigments (rutile) followed by 15 parts of solid carbon dioxide. 400 Parts of the NCO prepolymer solution are stirred into this suspension within a few minutes, an elastomer solution having a viscosity of 565 poises/C being formed. Portions of the solution were treated with 2 percent of phenol stabilisers (a) or light protective agent or 2 percent of the synergistic mixture of (a) and (b) or the mixture according to Dutch Patent 6,509,745. Films were produced in known manner from portions of solution with and without stabiliser, and these films were exposed in a Fadeometer (see Table 10).

The results show that the new Stabiliser mixture provide substantially better protection against discolouration and mechanical degradation than the individual components.

Similar good results are obtained by using 2 percent of mixtures of the phenol stabilisers (a) which are indicated in Table 1 by (B), (C) and (D), and light protective agents (b) such as 2-(2'-hydroxy-3',5-ditertiaryamylphenyl)-benz0triaz0le or 2-(2-hydroxy'5-methylphenyl)-benzotriazole in proportions of 2:1 to 1:2.

TABLE 10 Fadeometcr Exposure Additives 22 Hours 44 Hours None Foils yellow, Foils yellow brown;

complete mechanical Destroyed degradation 2% Stabiliser A Foil colorless, Foil almost colorless,

strength substantially maintained mechanical strength maintained (component a) mechanical strength largely maintained (component a) Foil yellowish. mechanical strength 1% Stabiliser E 1% 2-(2'-hydroxy-3,5-

Foil colorless, mechanical strength ditertiary maintained largely maintained butylphenyl)-5- chloro-benzotriazole (synergistic mixture) 2% Foil yellowish Foil yellow. mechanical 2-(2'-hydroxy-3'-N- mechanical strength degradation methylenesubstantially phthalimido)- maintained benzotriazole (component b) Foil almost colorless. mechanical strength substantially maintained 1% Stabiliser E 1% 2'(2"hydroxy-3'-N- methylenephthalimido)- benzotriazole (synergistic mixture) Foil colorless, mechanical strength maintained EXAMPLE The elastomer solutions with and without stabiliser 800 Parts of a polytetramethylene ether diol (OH are painted on glass plates and dried at 100C for number 1 l 1) are heated to to for 50 minutes minutes. The elastomer films which are about 0.15 to with 17.4 parts of N,N bis (B hydmXyprOpyl) N 5 0.20 mm thick are cut up nto threads of about 300 den methylamine, 3066 parts of diPhenYlmethaneAAk with a f0|l cutting machine and then exposed to UV diisocyanate and 284 parts ofchlorobenzene and then hght m an ATLAS Fade'o'meter for 44 and 66 cooled to room temperature. 800 parts of the NCO prehours (Table l 1 polymer solution obtained 1.9 percent NCO) are stirred together with a solution of 38.7 parts of 4,4- 10 EXAMPLE 11 diaminodiphenylmethane in 1,872 parts of dimethyl- 800 Parts of a polytetramethylene ether diol (OH formamide, and after 12 hours, 3.38 parts of diphenylnumber 111) are heated to C for 40 minutes with methane-4,4-diisocyanate are added, a viscous elasto- 18.0 parts of N,N-bis-(B-hydroxypropyl)-N- mer solution 102 poises/20C) being obtained to methylamine, 394.5 parts of diphenylmethane-4,4'- which 1 part of acetic anhydride per parts of solu- 15 diisocyanate and 304 parts of chlorobenzene, an NCO tion is added. The solution is pigmented by the addition prepolymer being formed which contains 3.58 percent of 4 percent titanium dioxide (rutile) based on the of NCO after cooling to room temperature. amount of solid elastomer substance.

Portions of the above elastomer solution are treated ELASTOMER SOLUTION I: with 2 percent of the stabilizer mixture according to the 20 404 Parts Of the NCO p p y Solution t Stirred invention and for comparison with 2 percent of compotogether with 3.30 parts of water in.889 parts of dinents a) and b) and the mixture according to Dutch methylformamide at room temperature, the solution Pat. No. 6,509,745. turns yellow after about one hour and a highly viscous TABLE 11 initially 22 Hours 44 Hours 66 Hours Tensile Elongation at Tensile Elongation at Tensile Elongation at Tensile Elongation at Strength g/den break Strength g/den break Strength g/den break Strength g/den break 71 Without stabiliser 0.05

yellow brown yellow brown brownish yellow 2% stabiliser 0.66 605 0.60 620 0.53 621 0.17 400 A (Part component of the synergistic mixture colorless colorless colorless 2% 0.66 610 0.16 no longer measurable 2-hydroxy- 3-tertiary butyl-5- methylphenyl- )-5-chlorobenzotriazolc (Part component of the synergistic mixture) yellowish yellowish yellow 1% Stahiliscr 0.66 620 0.67 621 0.68 604 0.53 610 A 17! 2"hydroxy- 3'-tertiary butyl-S methylphenyl- )-5-chlorobenzotriazole (synergistically active mixture colorless colorless colourless 1% lONOX 0.65 610 0.54 605 0.33 604 0.16 387 330 1% -(2'hydrox v- 3'-tertiary butyl 5'- methylphenyl- )-5-chlorobenzotriazole (comparison test according to Dutch 6.509.745)

colorless colorless yellowish The synergistic mixture is shown to be effective for much longer than the individual components and is distinctly superior to the stabiliser mixture according to Dutch 6.509.745.

elastomer solution with a strong yellow colour being obtained after 24 hours. When the solution is spun by the usual dry spinning process, yellow elastomer threads are obtained.

ELASTOMER SOLUTION II:

404 Parts of the NCO prepolymer solution are stirred together with 3.30 parts of water and 4.87 parts of stabiliser A( 1.5 percent by weight) and 1.63 parts percent by weight) of the light protective agent 2-(2'- hydroxy-3 ,5 -ditertiary-amylphenyl)-benzotriazole in 890 parts of dimethylformamide at room temperature, a highly viscous, completely colourless elastomer solutionbeing obtained after 24 hours, which solution yields colourless elastomer threads when spun by the usual dry spinning process, which elastomer threads are also much more stable against discolouration and mechanical degradation on exposure to light or treatment with hot air than the threads from elastomer solution 1.

If elastomer solution 1 is treated with 2 percent by weight of the mixture of 1.5 percent of stabiliser A and 0.5 percent light protective agent (see above), slightly coloured elastomer threads are obtained which are much more stable on exposure to light or hot air treatment (e.g., one hour at 150C) than the threads from elastomer solution I without the addition of stabiliser.

EXAMPLE 12 800 Parts of polytetramethylene ether diol, molecular weight 1,010, are heated with 297 parts of diphenylmethane4,4-diisocyanate and 223 parts of chlorobenzene for 38 minutes at 80C to form the NCO prepolymer. By stirring 419 parts of the prepolymer into an approximately 60C hot solution of l 1.56 parts of carbodihydrazide in 916 parts of dimethylformamide, a highly viscous elastomer solution (552 poises) is obtained which is pigmented with 4 percent TiO A part of this solution is treated with 1 percent by weight of stabiliser A (based on solid substance) and another part is left without stabiliser. Films obtained from the solutions show the following properties after exposure in the Fadeometer:

TABLE 12 Tensile strength (in g/den) after Fadeometer exposure (in hours):

without additive 0.68 0.27 no longer measurable 2% Stabiliser A 0.70 0.69 0.30 0.27

+ 1% Stabiliser A 1% 2-(2'-hydroxy-3-tertiary-butyl-5-methylphenyl)-5-chloro-benzotriazol- 0.70 0.69 0.61 0.59 0.51

What we claim is: 1. A compound of the formula on 0 CH; OH: I

crn- -cm cmx I Hi Q where Q is OCH or tertiary octyl and X is CH; 0CH3 

2. 2,4-Dimethyl-6-(2''-hydroxy-3''-tertiary-butyl-5''-methylbenzyl)-anisole.
 3. 4-Tertiary-octyl-2,6-bis-(2''-hydroxy-3''-tertiary-butyl-5''-methyl-benzyl) -anisole.
 4. 2,6-Bis-(2''-hydroxy-3''-tert.-butyl-5''-methyl-benzyl)-hydrochinon -dimethylether. 